Plavix gets black box

FDA added a black box warning to the label of Plavix clopidogrel concerning the drug's diminished effectiveness in patients with a genetic variation in cytochrome P450 2C19 (CYP2C19). The agency noted that people who have reduced functioning of their CYP2C19 liver enzyme cannot effectively convert Plavix to its active form. The agency estimated that 2-14% of the U.S. population are "CYP2C19 poor metabolizers." ...